The emergence of new diseases like the pandemic influenza H1N1, and the reemergence of old threats like mumps, pertussis, pneumococcal disease and measles should serve as a reminder to physicians and patients about the importance of immunization, according to a speaker here at the 44th National Immunization Conference.

Pandemic H1N1 influenza emerged as a new virus and caused more pediatric deaths in the past 12 months than in any previous season, according to Jane Seward, MBBS, MPH,deputy director of the division of viral diseases at the CDC. Seward said since the pandemic emerged in the United States last April, it has caused more than 15 million cases, 270 hospitalizations and more than 12,000 deaths, despite an available vaccine.

Although rates of mumps have declined since the vaccine was first introduced, sporadic mumps outbreaks, including the most recent that began last summer at a summer camp and has now affected more than 1,520 people in New York and New Jersey, show that this illness poses a continuing challenge, Seward said. Although mumps incidence hit its lowest point in four decades between 2002 and 2005, sporadic outbreaks in different pockets of the United States have sent rates from 268 cases per year to more than 2,000 reported cases per year during the past four years.

Although most children during the New York and New Jersey outbreaks had received two doses of the measles-mumps-rubella vaccine, waning immunity may have contributed to the outbreaks. Seward said vaccination likely prevented the mumps outbreak from spreading farther. She also noted that introducing a third dose in the most recent outbreak seems to be having a positive effect, although it is too early to draw conclusions.

Pertussis also presents a continuing challenge, with 8,000 to 25,000 cases reported per year. Seward said priorities for pertussis control include evaluating the adolescent vaccine